<!DOCTYPE html>
<style>
    div { position: relative; }
</style>
PASS if there is no red visible.
<!-- This div should be snapped up to (1,1) -->
<div style="width: 70px; height: 70px; left: 0.7px; top: 0.7px;">
    <div style="background: red; width: 40px; height: 40px; transform: translateZ(0);">
        <!-- Because the first div is snapped up to (1,1), this div will start with a -->
        <!-- paint offset of (-0.3,-0.3) which will be added to (0.7,0.7) to get -->
        <!-- (0.4,0.4) which rounds down to (0,0) and obscures the red div. -->
        <div style="background: white; width: 40px; height: 40px; left: 0.7px; top: 0.7px;"></div>
    </div>
</div>
